1. Field of the Invention
The present invention relates to a smart window including an electrochromic device and an organic light-emitting device.
2. Description of the Related Art
Generally, an organic light-emitting device includes an anode, a light-emitting layer disposed on the anode, and a cathode disposed on the light-emitting layer. When a voltage is applied between the anode and the cathode, holes are injected from the anode into the light-emitting layer, and electrons are injected from the cathode into the light-emitting layer. The holes and electrons injected into the light-emitting layer are recombined with each other to generate excitons, and such excitons are shifted from an excited state to a ground state to emit light.
Such an organic light-emitting device may be classified into a bottom emission type organic light-emitting device in which the light emitted from the light-emitting layer transmits the lower substrate adjacent to the anode and a top emission type organic light-emitting device in which the light emitted from the light-emitting layer transmits the upper substrate adjacent to the cathode. Further, such an organic light-emitting device may be realized as a dual emission type organic light-emitting device in which light is emitted to both bottom and top sides using a transparent anode and a transparent cathode.
The transparent organic light-emitting device realized as the dual emission type organic light-emitting device can be realized into a smart window, and, particularly, can be configured such that one side light emission or double side light emission can be selectively carried out by blocking or transmitting light by attaching an electrochromic device to one side thereof and controlling the color of the electrochromic device.
However, when the organic light-emitting device is realized as the dual emission type organic light-emitting device using a transparent anode and a transparent cathode, one side light emission or double side light emission can be selectively carried out by controlling the color of the electrochromic device, but there is a problem in that the light efficiency of this dual emission type organic light-emitting device is greatly lowered compared to that of a bottom emission type organic light-emitting device or a top emission type organic light-emitting device at the time of one side light emission, and the contrast ratio thereof is also lowered.
The present inventors have intensively made an effort to improve the light efficiency of an organic light-emitting device at the time of realizing a smart window by combining an electrochromic device with the organic light-emitting device. As a result, they found that the light efficiency and contrast ratio of the organic light-emitting device can be greatly improved by replacing a transparent electrode of a conventional organic light-emitting device disposed adjacent the electrochromic device with a high-reflection electrode and forming a predetermined light transmission portion. Based on the findings, the present invention has been completed.